From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756884AbdABWoN (ORCPT ); Mon, 2 Jan 2017 17:44:13 -0500 Received: from mail-pg0-f68.google.com ([74.125.83.68]:35067 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755431AbdABWoA (ORCPT ); Mon, 2 Jan 2017 17:44:00 -0500 Subject: Re: [PATCH net 9/9] virtio-net: XDP support for small buffers To: Jason Wang , mst@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <1482503852-12438-1-git-send-email-jasowang@redhat.com> <1482503852-12438-10-git-send-email-jasowang@redhat.com> Cc: john.r.fastabend@intel.com From: John Fastabend Message-ID: <586AD79B.2070203@gmail.com> Date: Mon, 2 Jan 2017 14:43:39 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1482503852-12438-10-git-send-email-jasowang@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16-12-23 06:37 AM, Jason Wang wrote: > Commit f600b6905015 ("virtio_net: Add XDP support") leaves the case of > small receive buffer untouched. This will confuse the user who want to > set XDP but use small buffers. Other than forbid XDP in small buffer > mode, let's make it work. XDP then can only work at skb->data since > virtio-net create skbs during refill, this is sub optimal which could > be optimized in the future. > > Cc: John Fastabend > Signed-off-by: Jason Wang > --- > drivers/net/virtio_net.c | 112 ++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 87 insertions(+), 25 deletions(-) > Hi Jason, I was doing some more testing on this what do you think about doing this so that free_unused_bufs() handles the buffer free with dev_kfree_skb() instead of put_page in small receive mode. Seems more correct to me. diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 783e842..27ff76c 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1898,6 +1898,10 @@ static void free_receive_page_frags(struct virtnet_info *vi) static bool is_xdp_queue(struct virtnet_info *vi, int q) { + /* For small receive mode always use kfree_skb variants */ + if (!vi->mergeable_rx_bufs) + return false; + if (q < (vi->curr_queue_pairs - vi->xdp_queue_pairs)) return false; else if (q < vi->curr_queue_pairs) patch is untested just spotted doing code review. Thanks, John